Question

利用公式求下列三角函數(shù)值：

(1)cos(-510°15′);  (2)sin(-).

Answer 1

解:(1)cos(-510°15′)= cos510°15′=cos(360°+150°15′)

=cos150°15′=cos(180°-29°45′)=-cos29°45′=-0.868 2.

(2)sin(-)=sin(-3×2π)=sin=